Campbell says he has suffered from chronic pain since surgery he had in 2009. He started by controlling his pain with fentanyl, but disliked it — “Fentanyl scares me. I’m totally scared to death of it.” His doctor switched him to hydromorph contin, and he has been gradually able to cut his dosage by over two-thirds by using cannabis oil, and hopes to cut it further.

“When your body gets accustomed to a specific product, and you’re buying it from a specific company, it gets adjusted to it. To try to change over to another supplier makes it difficult.”

Tilray saw higher demand from medical customers in the leadup to recreational legalization, the company says. After it sent them e-mails warning them of a possible shortage, a rash of buying worsened the shortage.

“We have received an unusually high volume of orders on Tilray medical cannabis products this month,” said spokesperson Chrissy Roebuck in an e-mailed statement. “In anticipation of a potential stock-out of whole flower, we proactively informed patients of this temporary supply interruption which resulted in an additional high volume of orders on oil and capsule varieties, as well.”

In an e-mailed statement, Health Canada pointed to a sharp increase in licenced production capacity: 89 new facilities have been licensed in the last 16 months and another 179 allowed to expand.

“The Government of Canada is committed to ensuring that Canadians who require cannabis for medical purposes have access to a legal and quality-controlled supply,” spokesperson Tammy Jarbeau wrote.

“While there is no regulatory requirement for licensed producers to prioritize sales to individuals who require cannabis for medical purposes over non-medical sales, it is expected that they will do so. In fact, a number of existing licensed producers have committed publicly to doing so.”

“There used to be a restriction on the amount you could purchase in a 30-day period, and that’s been removed. While that’s a good thing, because it did create supply uncertainty for patients, and that’s the reason it was removed, suddenly the buying levels doubled or tripled.”

And it would be unhelpful to try to bring it back, she argues.

“You’d be doing that on the basis of assumptions that patients would continue to buy exactly what they’re buying now in exactly the same quantities that they’re buying now, and that they’re not going to make a different choice. It can’t be done.”

It’s legally possible for producers to import medical marijuana (they can’t import recreational marijuana). But Ottawa is unlikely to approve that because of uneasiness about the quality of the imported product, Fraser says.

On Twitter, the company said it was hoping to restock by the end of October.

Our team is working diligently to expedite products to the store! We have additional whole flower, 10:10 Balance and 25:0 THC oil expected by the end of the month; High-CBD oil in early November!

We understand access to our products is paramount and our team is committed to ensuring the store is well-stocked with a diverse selection for patients to select from. We anticipate being stocked up as early as next week. Thank you for your patience.

But buying up a large supply is only open to those who can afford it, Campbell points out.

“You’d have to have an awful lot of money to do that. When I purchase mine, I usually buy three bottles at a time. They don’t last a week, and that’s $269 for those three bottles. I’m on a limited income, and that’s quite difficult.”

WATCH: Why is the medical community so hesitant to endorse the pharmaceutical properties of marijuana?

Other licensed producers seem to be doing better than Tilray, at least for now.

Spectrum, Tweed’s medical division, still has a selection of gel caps, oils and dried flower, as does Aphria, though some of its strains are sold out. Aurora and WeedMD have a selection of oil and flower, as does Medreleaf, though many of its medical products are sold out. Maricann is offering two oils and a flower, down from three oils and two flowers on Oct. 12.